The popularity of Peanuts in its heyday - from the mid-1950s through to the late 1970s - was awe-inspiring to behold. Syndicated in over 1,000 newspapers worldwide, and read daily by more than 90m people, the strip was adored by hippies and hawks, evangelicals and existentialists alike. “No matter how rough things get, Peanuts gets my morning off a to a pleasant start and I find myself chuckling all the way to the Capitol,” said Ronald Reagan, while the Grateful Dead's Ron McKernan turned Pigpen into a role model for the flower-power generation. Try and imagine a figure that could unite both George Bush and Radiohead's Thom Yorke in such boundless devotion and you realise what demographic heft Peanuts wielded. At one point a copy of the spin-off book Happiness Is a Warm Puppy was selling every 30 seconds. “There goes another one,” Peanuts creator Charles Schulz would joke, struggling to find ways to shrug off his success. The first living cartoonist to be honoured with a retrospective at the Louvre, he told Time, “I'm no Andrew Wyeth.” A few weeks later, he received a call of congratulations from Wyeth. Good grief.

Like many popular artists, Schulz (1922-2000) spent his childhood feeling about as popular as a pea, as David Michaelis's biography makes clear. Shy, lonely, awkward, he stayed indoors drawing, or else nursing unrequited crushes on the girls at school. “Did you know a Marie Holland from Needles?” he would ask, well into middle age, if someone said they hailed from one of his old neighbourhoods, although all he had done at the time was walk to the corner with the girl. Did she remember him? Had she noticed him? The man knew how to hold a grudge - even in his late sixties he recalled his drawings being rejected by the school yearbook as if it were yesterday - and emerges from Michaelis's book as a cross between a bruised peach and a prickly pear, possessed of the strange egotism of the shy. “Arrested, bitter,” writes Michaelis, “he spent a startling amount of time over nearly 60 years polishing a cameo of boyish helplessness and frustration.” By the time an actual blow does arrive (the death of his mother from cancer when he was 19) it feels oddly redundant, somehow, so automatic is the flinch with which Schulz shields himself from the world.

It was the second world war, strangely, that brought him out of himself. Schulz went into the service “a nothing person”, and came out an expert marksman and sergeant in charge of a machine-gun squadron that had marched through Dachau. Afterwards, he set about his ambition to become a syndicated cartoonist with salmon-like zeal. His first strip, Li'l Folks, bewildered editors (Why did the kids all talk like grown ups? Why were their heads so big?), although, as Li'l Folks segued into Peanuts, their heads got bigger. Other cartoonists were trying to make the most of their space by cramming it with action and ink: Schulz emptied the frame, filling it with white space, dropping traditional gags in favour of plotlines in which one kid fooled another into eating mashed potato instead of ice cream. “It was hard to understand,” said one veteran cartoonist. “I'd read Peanuts some days and at the end it was just ‘sigh'. I'd think: that's not a gag line. What's he doing?”

Newspaper cartoons may have never seen anything like it, but those dying falls contained uncanny echoes of the humdrum rhythm with which most of us live our lives. No rage, no tears, no self-pity, no punchline - just silent endurance of the slights and insults that Charlie Brown picks up in the course of a day, like moss. “I don't feel the way I'm supposed to feel,” he confided, his silent fortitude indicated simply by a couple of parentheses on either side of his eyes, like a frown that had slipped. What Schulz did feels almost as revolutionary in its way as the invention of the close-up in cinema, since it allowed him fine-grained focus on all the minor-league emotions - chagrin, disappointment, melancholy, longing - that don't normally make it to the front of the class. Only Lucy lets rip, with screams that required a B5 pen - “AAAARRGHG!” - and a B3 for “maximum screams”. She was modelled partly on Schulz's wife, Joyce, a headstrong adventuress with reddish-blonde hair, blue eyes and a saddle of freckles on her nose. Schulz compared her to a “speeding bullet”. The marriage would last 20 years, but the friction between them would provide the crackle for all the ill-matched couples in Schulz's work, not least Lucy's infatuation with the child prodigy Schroeder, his head bent over his miniature piano. (“Never in all my life did I expect to play second fiddle to a metronome,” she complains.)

One of the great coups of Michaelis's biography is the deftness with which he crosscuts between Schulz's life and work, particularly when his marriage was winding down and he strayed into an affair with a photographer, Tracey Claudius. He was an absolutely hopeless adulterer, needless to say, puppyishly besotted and fabulously indiscreet. His phone calls “were like sitting through Dr Zhivago: everything was a drama, everything was a parting”, said Claudius, who rightly realised that Schulz's tumultuous feelings had little to do with her and backed away. The marriage broke up, and Schulz commemorated the fact with a slightly heartless strip in which Charlie Brown fires Lucy from the baseball team. “Isn't it nice not having her around?” he beams. “Isn't it nice not hearing her voice?”

Michaelis's biography has caused some uproar among Schulz's surviving family members, his daughter insisting that he was a “Christlike father”, omitting to mention whether “Christlike” is an admirable quality in a father. It's what you get, I guess, for writing a biography as exemplary as this - rich, honest, humane and warmed by unfakeable admiration for the work. As Michaelis freely admits, nobody could peel Schulz better than Schulz himself. “I supposed I'm the worst kind of egotist, the kind who pretends to be humble,” he said and his work displays all the sardonic self-knowledge that came to him only patchily in his daily life. He eventually achieved a measure of happiness with a second wife, “a suntanned package of energy” 16 years his junior, and his final decade of drawings gave off a mellow, Californian glow, with jokes about health, exercise, tennis and acupuncture. “Like Katharine Hepburn, who turned to advantage even the quaver in her ageing voice, Schulz found new warmth in his wavering line,” before succumbing to colon cancer in his seventies.

His one regret, he said, was that he never once let Charlie Brown kick the football held out for him by Lucy: always she snatched it away and always he landed on his back. What private frustrations that unkicked football represents one can only guess at, so perhaps the last word should be left to Linus, Schulz's favourite character to draw. In one strip, he is trying to wheedle Lucy into reading a story to him. Exasperated, she grabs a book at random from the shelf - “A man was born, he lived and he died. The End!” she says and tosses the book aside. Linus picks it up reverently. “What a fascinating account,” he says. “It almost makes you wish you had known the fellow.”

Schulz and Peanuts by David Michaelis
Harper Collins £11.99 pp655

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